Polarizabilities (alpha) of dendritic molecular aggregates: Visualization of intermolecular-interaction and damping effects on alpha

We investigate the intermolecular-interaction and damping (among exciton st ates) effects an the polarizabilities (alpha) for molecular aggregates with different sizes of planar dendritic, i.e., Bethe-lattice (or Cayley-tree), structures by elucidating the spatial contribution of one-exciton generati on to alpha. The molecular aggregate is treated in the one-exciton model, i ncluding the dipole-dipole interaction. The off-resonant or of the molecula r aggregate is calculated by the numerical Liouville approach, including th e damping effects. The signs of the contribution of intermolecular-interact ion (positive) and damping (negative) effects to alpha are found to be oppo site with each other. The magnitude of these effects on or indicates a nonl inear enhancement as the number of monomers increases. These effects on alp ha for the fractal-structured dendritic aggregates are also found to provid e distinct spatial contributions for different generations of the dendritic structure in contrast to the case of a non-fractal-structured dendritic ag gregate.